18 results about "Heterodyne interferometry" patented technology

The invention relates to the technical field of semiconductor lasers, in particular to a DFB laser based on a top metal grating, and the DFB laser comprises a gain chip, the left end face of the gain chip is plated with a high-reflection HR film, and the right end face of the gain chip is plated with an anti-reflection AR film; the upper end face of the gain chip is provided with a ridge optical waveguide, and the upper end face of the ridge optical waveguide is provided with a metal Bragg reflection grating layer. A self-heterodyne interference method (the line width of a local oscillator is smaller than 500 Hz) is adopted, and the measured value of the 3dB line width is 50 Hz (the measured value of a traditional DFB is 125 kHz). The mode purity degree is verified through a Lorenzian fitting broadening factor 1.15; the wavelength drift is less than 0.05 pm / DEG C within the range of-40 DEG C to 85 DEG C after compensation of the temperature compensation circuit. The temperature tuning coefficient is 0.08 pm / DEG C, the current tuning coefficient is 0.05 pm / mA, and the tuning coverage range is 1530-1545 nm.

This invention discloses a heterodyne digital holographic microscopic phase imaging scheme based on a moving grating. The scheme includes an optical imaging device and a measurement method. The optical imaging device includes a light source system, an amplification system, a heterodyne interferometry system, and an image acquisition system. A light beam emitted from the light source penetrates the object under test, carrying the object's optical phase information. This information is amplified by the amplification system and then passed through a moving grating in the heterodyne microscopy system, splitting the incident light into multiple beams of different frequencies. An aperture is used to select the 0th and +1st order beams, which interfere on the camera's detection surface to generate continuous moving interference fringes. The measurement method mainly includes: optical path adjustment, image data acquisition, image processing, and phase-height calibration. This invention achieves higher reconstruction accuracy compared to traditional single-image reconstruction schemes, and features low cost and good stability, providing a new measurement scheme and approach for digital holographic microscopy.

An optical heterodyne interference measurement device (1) is provided with a light beam generation unit (10), a beam splitter (21), a mirror (31), a first light detector (41), a linear polarizing plate (42), a second light detector (51), a linear polarizing plate (52), an AD conversion unit (60), and a computer (70). The first light detector (41) receives light output from the linear polarizing plate (42), detects a temporal change in light intensity thereof, and outputs a first detection signal (measurement signal). A second light detector (51) receives the light output from the linear polarizing plate (52), detects a temporal change in the light intensity thereof, and outputs a second detection signal (reference signal). The computer (70) acquires information pertaining to the object to be measured (90) on the basis of a signal obtained by fitting the measurement signals within the interval using a sine function for each interval starting from the timing at which the reference signal has reached the prescribed value. As a result, an optical heterodyne interference measurement device capable of suppressing a decrease in measurement accuracy is achieved.

The application provides a kind of space telescope structure stability on-orbit test method and system, according to the measurement accuracy requirement of space task and the stability requirement of telescope, a kind of high-precision space telescope structure stability on-orbit test method combining heterodyne interferometry, differential wavefront phase detection (DWS) is proposed.Through intercepting part of the outgoing light for interference, the structural stability change of the space telescope is obtained without affecting the measurement task.The interferometer structure adopted by the method and system of the application is stable and compact, has the characteristics of small volume, light weight and high precision, and meets the test requirements of the structural stability of the satellite-borne telescope.

This invention discloses a laser linewidth measurement device and method based on switchable channel delay self-heterodyne interferometry, belonging to the field of laser linewidth measurement technology. The laser to be measured is incident on a first fiber coupler via an isolator and splits into two paths: one path enters a computer-controlled first and second optical switches via a three-port fiber circulator, switching between different lengths of delay fiber via the first and second optical switches, rotating the polarization state by 90° via a Faraday rotating mirror before returning along the original path, and then restoring the original polarization state via a polarization controller; the other path undergoes frequency shifting via an acousto-optic frequency shifter. The two paths are combined via a second fiber coupler to generate a beat frequency optical signal, which is then acquired by a photodetector for photoelectric conversion and a spectrum analysis module. The computer fits the beat frequency power spectrum corresponding to different delay lengths to obtain the laser linewidth to be measured. This invention has strong anti-interference capabilities and can simultaneously acquire Lorentz linewidth, Gaussian linewidth, and composite linewidth, with a wide linewidth measurement range.

The invention provides a dual-thread complementary algebraic derivative estimation compensation algorithm based on an FPGA (Field Programmable Gate Array). The method is characterized in that a reference signal and a measurement signal enter an FPGA after passing through ADC1 and ADC2 modules and then respectively pass through a biorthogonal phase-locked amplification module 3 and a phase difference module 4 in the FPGA, a pair of orthogonal signals only containing Doppler frequency shift is obtained after passing through a phase difference module 5, and then the signals enter a double-thread complementary data aging error compensation (DAEC) module 6 for compensation; the calculated signal does not contain the aging error, and finally, a Cordic calculation module 7 is utilized to obtain a final phase, and the final phase is calculated. The FPGA implementation method can be used for compensating the data aging error in a heterodyne interference measurement system, and can be widely applied to the fields of displacement measurement, position control, position sensor calibration, platform calibration and the like.

This invention belongs to the field of three-degree-of-freedom pose measurement technology, and relates to a single-beam three-degree-of-freedom pose measurement method and device based on heterodyne interferometry and self-collimation. The measurement method includes the following steps: Step 1: A laser beam is split into two beams with a certain frequency difference; Step 2: In the self-collimation module, the laser is split into a first reference beam and a first beam; the first beam is modulated, reflected, and then modulated again to split into a first measurement beam and a second beam; the second beam is modulated to a first photoelectric detection module; Step 3: In the heterodyne interferometry optical path, the laser is split into a second reference beam and a third beam; the third beam is modulated, reflected, and then split into a second measurement beam and a fourth beam; the two reference beams are merged to form a first interference beam, and the two measurement beams are merged to form a second interference beam; Step 4: A circuit module acquires the angle and displacement; The measurement device includes an optomechanical module, a target under test, and a circuit module. Using the above scheme, displacement and angle are measured simultaneously.

The invention refers to a frequency shifter for heterodyne interferometry measurements, comprising a chip, an input waveguide configured to guide a light beam, at least four phase modulators, each being arranged to receive the light beam from the input waveguide and configured to modulate a phase of the light beam, an output combiner being arranged to let the light beams modulated by each phase modulator interfere, a first output waveguide coupled to the output combiner and configured to receive the modulated light beams constructively interfering at the output combiner, a second output waveguide coupled to the output combiner and configured to receive the modulated light beams destructively interfering at the output combiner, wherein the input waveguide, the phase modulators, the output combiner, the first output waveguide and the second output waveguide are arranged on the chip.

A three-degree-of-freedom heterodyne interferometer device with angle information recovery and a method thereof belong to the technical field of laser interferometry. The device comprises a heterodyne light source, a heterodyne interference mirror group, a wavefront control target mirror, an angle information recovery optical path, an optoelectronic conversion unit and an electronic signal processing unit. The heterodyne light source outputs two beams of light with different frequencies, and the beams are divided into measurement light and reference light by the interference mirror group; the wavefront control target mirror is deflected with the measured object to ensure the effectiveness of the light beam interference under a large angle; the angle information recovery optical path converts the change of the optical axis position of the light beam into the difference in the focal plane phase distribution, and then the difference is sampled by a fiber array. The optoelectronic conversion unit completes the conversion of the optoelectronic signal, the rear-end processing unit demodulates the phase, and the displacement, pitch angle and yaw angle of the measured object are calculated. The present application solves the problem that the angle information is difficult to extract under a large angle in the existing scheme, expands the angle measurement range, and the device structure is compact and has high integration, and three-degree-of-freedom synchronous high-precision measurement can be realized.

The invention discloses a backward stray light detection method based on a heterodyne interference measurement principle, and the method comprises the steps: obtaining an actual received signal of a telescope, taking a small amount of emitted light beams as local reference laser, carrying out the interference with the received light beams, enabling a fixed frequency difference to exist, carrying out the balance detection of the actual received signal, obtaining a heterodyne signal, and carrying out the detection of the backward stray light according to the heterodyne signal. And phase information of back stray light is determined. Local reference laser is used for carrying out balance detection on an actual received signal, the local reference laser with large power and backward stray light with small power can be used for forming coherent laser superposition with a fixed frequency difference, and phase information of the backward stray light can be obtained from a light beat phenomenon generated by an obtained heterodyne signal. The phase information of the back stray light can be detected under the condition that the back stray light is weak, and data support is provided for elimination of the back stray light and use, maintenance and design of a telescope. The method is widely applied to the technical field of stray light detection.

The invention discloses a lateral deviation measurement system and method based on modulated sine waves, and belongs to the technical field of space laser interference and optical precision measurement, and the method comprises the steps: in a laser heterodyne interference measurement and control system, an advanced pointing mechanism is driven to make periodic sine deflection with the frequency of Y. Detecting a phase value of a beat frequency signal in the four-quadrant detector through a phase meter; decoupling a time domain light beam included angle and a time domain optical path difference; solving a logarithmic amplitude spectral density function of the light beam included angle and the optical path difference; solving a complex mode of the logarithmic amplitude spectral density function of the light beam included angle and the optical path difference at the frequency of the modulated sinusoidal signal; calculating lateral offset through the complex modulus ratio of the optical path difference to the light beam included angle; and judging whether the lateral offset is smaller than a threshold value, if so, inhibiting the TTL coupling effect, otherwise, adjusting the high-precision displacement table through the controller to reduce the lateral offset, and circulating the steps until the lateral offset is smaller than the threshold value. According to the invention, high-precision quantization and suppression of lateral offset are realized.

This invention discloses a device and method for testing the dynamic performance of a pendulum based on a laser heterodyne interferometer. The pendulum driving module of this invention applies a dynamic acceleration signal with adjustable amplitude and frequency to the clamping fixture and the pendulum under test via piezoelectric ceramics. Then, the dynamic displacement response of the clamping fixture and the pendulum under test is simultaneously detected through the heterodyne interferometry optical path. Next, the theoretical displacement signal of the pendulum under test driven by the piezoelectric ceramics and the actual displacement signals of the clamping fixture and the pendulum under test are obtained through a signal acquisition system. Finally, signal processing and data comparison are performed by a terminal computer to obtain the dynamic response characteristics of the pendulum under test under applied excitation within and outside the bandwidth and range. The device of this invention is simple and reliable, has a wide measurement range, extremely high testing accuracy, and strong anti-electromagnetic interference capability.

A heterodyne interferometer device and method based on wavefront regulation target mirror belong to laser interferometer measurement technical field, the present application solves the problem of insufficient system interference keeping ability under the condition of large angle deflection of target mirror. The device comprises a heterodyne interference mirror group and a wavefront regulation target mirror, the heterodyne interference mirror group separates a bundle of input light beams into a first measurement light beam and a first reference light beam, and separates another bundle of input light beams into a second measurement light beam and a second reference light beam, the wavefront regulation target mirror is installed on the measured object, and the second measurement light beam is reflected to form a return measurement light beam and returns to the heterodyne interference mirror group, when the measured object occurs angle deflection such as pitching or yawing in the movement process, the wavefront regulation target mirror deflects synchronously with the measured object, the return measurement light beam is parallel to the second measurement light beam, the change of the return measurement light beam caused by large angle deflection of the wavefront regulation target mirror is more manifested as the position translation of the optical axis, thereby weakening the angle mismatch and wavefront mismatch.

The present invention discloses a composite probe based on laser heterodyne interference technology, which relates to the technical field of monitoring. The present invention includes a probe. A round rod is provided at the bottom of the probe. A connecting plate is provided at the bottom of the round rod. A round frame is provided at the bottom of the connecting plate. A concave hole is provided at the bottom of the round frame. A water blocking mechanism is provided on the outer surface of the probe. A clamping mechanism is provided on the outer surface of the round rod. The number of the clamping mechanisms is two. An adjusting mechanism is provided at one end of the clamping mechanism away from the round rod. A fixing mechanism is provided inside the round frame. In the present invention, a circular ring frame is provided on the outer surface of the probe. When rainwater drops onto the surface of the circular ring frame, it will slide down through the slope of the inclined plate to protect the surface of the probe. The circular ring frame is separated from the surface of the probe through a connecting rod, so that the inclined plate can be inclined on the top of the probe to reduce the contact between the oblique rain and the probe.

The invention discloses a vacuum temperature measuring device based on heterodyne interference, which is used for measuring tiny temperature fluctuation in a closed heat insulation space in a non-contact and high-precision manner, and belongs to the technical field of precision measurement. The device comprises a double-frequency heterodyne interferometer, a heat insulation box body, a vacuum cavity for accommodating the heat insulation box body and an aluminum pipe arranged in the heat insulation box body. Double-frequency orthogonal polarized light emitted by an interferometer located outside the vacuum cavity is split into reference light and measuring light through the optical assembly, and the reference light and the measuring light are reflected by the semicircular reflectors at the two ends of the aluminum tube respectively and then are combined for interference. The optical path change caused by thermal expansion and cold contraction of the aluminum pipe is calculated by detecting the phase change of the interference signal, and the temperature change in the heat insulation box body is inversed in combination with the thermal expansion coefficient. The device operates in vacuum, avoids air refractive index interference, has common-mode noise suppression capability, and is suitable for gravitational wave detection and other high-precision temperature measurement scenes.

This invention relates to a method and system for self-identification and compensation of errors in a three-degree-of-freedom heterodyne interferometry system, belonging to the field of laser interferometry technology. The method includes acquiring original axial displacement, pitch angle, and yaw angle measurement data; establishing a system error model that includes at least one of zero-position error, displacement angle coupling error, cosine error, channel drift error, and environmental drift error; fitting self-identification error compensation parameters based on initial state, preset small angle movements, short-stroke displacement movements, static output correlation, or multiple sets of data; statistically analyzing zero-position changes, drift trends, or residual changes during operation according to a sliding time window, updating drift compensation parameters, and using the current set of compensation parameters to perform online compensation on the original three-degree-of-freedom measurement results. This invention effectively improves the system's startup efficiency, multi-degree-of-freedom coupling error compensation capability, operational drift self-updating capability, and long-term measurement stability.

This invention discloses a method and apparatus for measuring the roll angle of a diffraction grating heterodyne interference based on a half-wave plate. The apparatus includes a non-polarizing beam-splitting prism disposed in the output optical path of a laser source; two parallel output optical paths each equipped with an acousto-optic modulator; a first non-polarizing beam-splitting prism disposed in the output optical path of the acousto-optic modulator; and a first quarter-wave plate, a first half-wave plate, a first transmission grating, a first combined reflector, a second non-polarizing beam-splitting prism, and a third non-polarizing beam-splitting prism disposed in the transmission optical path. In the reflected optical path, a first right-angle prism, a second quarter-wave plate, a second half-wave plate, a second transmission grating, a second combined reflector, a second right-angle prism, a third right-angle prism, and an optical space exchange are disposed. The output optical path of the first non-polarizing beam-splitting prism is equipped with a first polarizer, a first photodetector, a second polarizer, and a second photodetector. The detection signals of the two photodetectors are compared and calculated by a phase meter.

The invention refers to an optical device for heterodyne interferometry, comprising a chip, a beam splitter, a first waveguide arranged on the chip, light propagating in the first waveguide being guided to the beam splitter, a second waveguide arranged on the chip, light propagating in the second waveguide being guided to and / or from the beam splitter, wherein the beam splitter, the first waveguide, and the second waveguide form part of a Michelson interferometer, wherein the first waveguide and the second waveguide at least partially form two arms of the Michelson interferometer, and wherein two further arms of the Michelson interferometer are at least partially arranged outside the chip.